Linux: Use After Free
CVE-2026-45929 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 3e4fbcb4e078915367ba5576cd70d76dbc970f95, 442915c96a9bff1c7080e2aedabb1c03faa28d81, a5ec7baa44ea3a1d6aa0ca31c0ad82edf9affe41 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.16% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 3e4fbcb4e078915367ba5576cd70d76dbc970f95 or 442915c96a9bff1c7080e2aedabb1c03faa28d81 or a5ec7baa44ea3a1d6aa0ca31c0ad82edf9affe41, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.18.14 or 6.19.4, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 08857b5ec5d91d83e69e40a36554a8c7557b7301 up to, but not including, 3e4fbcb4e078915367ba5576cd70d76dbc970f95; 08857b5ec5d91d83e69e40a36554a8c7557b7301 up to, but not including, 442915c96a9bff1c7080e2aedabb1c03faa28d81; 08857b5ec5d91d83e69e40a36554a8c7557b7301 up to, but not including, a5ec7baa44ea3a1d6aa0ca31c0ad82edf9affe41; 6.16 | 3e4fbcb4e078915367ba5576cd70d76dbc970f95, 442915c96a9bff1c7080e2aedabb1c03faa28d81, a5ec7baa44ea3a1d6aa0ca31c0ad82edf9affe41 |
| Linux | Linux Kernel | 6.16 up to, but not including, 6.18.14; 6.19 up to, but not including, 6.19.4 | 6.18.14, 6.19.4 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: ovpn: fix possible use-after-free in ovpn_net_xmit When building the skb_list in ovpn_net_xmit, skb_share_check will free the original skb if it is shared. The current implementation continues to use the stale skb pointer for subsequent operations: - peer lookup, - skb_dst_drop (even though all segments produced by skb_gso_segment will have a dst attached), - ovpn_peer_stats_increment_tx. Fix this by moving the peer lookup and skb_dst_drop before segmentation so that the original skb is still valid when used. Return early if all segments fail skb_share_check and the list ends up empty. Also switch ovpn_peer_stats_increment_tx to use skb_list.next; the next patch fixes the stats logic.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Use After Free vulnerabilities
- 8.1 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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